In a display device such as a liquid crystal display device, a first substrate which is provided with a switching element such as a thin film transistor, and a second substrate which is provided with a color filter, etc., are attached to each other such that the first substrate and the second substrate are opposed to each other. The first substrate and the second substrate are glass substrates, for example, and since the first substrate and the second substrate are easily breakable at edges thereof, the strength needs to be improved at the edges.